Behavior of Compacted Magnesium-Based Powders for Energy-Storage Applications

Abstract

Energy storage is one of the main challenges to address in the near future—in particular due to the intermittent energy produced by extensive renewable energy production plants. The use of hydrides for this type of energy storage has many positive aspects. Hydride-based systems consist of absorption and desorption reactions that are strongly exothermic and endothermic, respectively. Heat management in the design of hydrogen storage tanks is an important issue, in order to ensure high-level performance in terms of the kinetics for hydrogen release/uptake and reasonable storage capacity. When loose powder is used, material in the form of pellets should be considered in order to avoid detrimental effects including decreased cycling performance. Moreover, sustainable materials in large-scale hydrogen reactors could be recovered and reused to improve any life cycle analysis of such systems. For these reasons, magnesium hydride was used in this study, as it is particularly suitable for hydrogen storage due to its high H2 storage capacity, reversibility and the low costs. Magnesium hydride was ball-milled in presence of 5 wt % Fe as a catalyst, then compacted with an uniaxial press after the addition of expanded natural graphite (ENG). The materials underwent 45 cycles in a Sievert’s type apparatus at 310 °C and eight bar, in order to study the kinetics and cycling stability. Scanning electron microscopy was used to investigate microstructural properties and failure phenomena. Together with Rietveld analysis, X-ray diffraction was performed for phase identification and structural information. The pellets demonstrated suitable cycling stability in terms of total hydrogen storage capacity and kinetics.

Positron Annihilation Spectroscopy Complex for Structural Defect Analysis in Metal–Hydrogen Systems

“…The process of hydrogen sorption by magnesium powder at a temperature of 400 °C and pressure of 30 atm stays very active because of the high specific surface area [ 38 , 39 , 40 ]. It can be seen that activated magnesium absorbed 2.3 wt.% in half an hour, and then hydrogen absorption by magnesium slowed down.…”

Beyond Hydrogen Storage—Metal Hydrides as Multifunctional Materials for Energy Storage and Conversion

“…Corgnale unequivocally presents an important approach to evaluating materials/systems for thermochemical energy storage, an approach that is relevant to any future analysis of such systems. Improved kinetic activity, increased storage capacity, scale-up, and long-term cycling stability are several important aspects related to the practical use of metal hydrides as emphasized in the article by Daniele M. Gattia et al [24]. This study describes the use of economically viable materials, ball-milled MgH 2 with the addition of Fe as a catalyst, plus the use of Expanded Natural Graphite to improve thermal conductivity within the compressed cylindrical pellets.…”